National Library Catalogs

• WorldCat - WorldCat is a catalog of materials held by libraries worldwide, including books, periodicals, sound recordings, musical scores, videos, manuscripts, and maps.
• Center for Research Libraries
• Other Library Catalogs and Websites

United States National Libraries

• Library of Congress Catalog
• Library of Congress World Wide Web
• National Agriculture Library
• National Archives and Records Administration
• National Library of Medicine World Wide Web

Canadian National Libraries

• National Research Council of Canada, includes the Canada Institute for Scientific and Technical Information (CISTI)

European National Libraries

• GABRIEL: Gateway and Bridge to Europe's National Libraries

Selected List of Massachusetts Library Catalogs

• American Antiquarian Society
• Boston Library Consortium Library (BLC) Catalogs
• Central & Western Mass. (C/W MARS)
• Fenway Libraries Online
• Five Colleges
• Harvard University Library System--HOLLIS
• Massachusetts General Hospital
• Merrimack Valley Library Consortium
• Minuteman Library Network
• MLIN List of Massachusetts Library Catalogs
• MLIN Web
• Noblenet
• Simmons College
• Williams College